1. Field of the Invention
The present invention provides a detection circuit, detection method and systems of measuring physical quantities such as a vibratory gyroscope or the like.
2. Related Art Statement
The inventors have studied various applications of a vibratory gyroscope. For example, it has been studied to use a vibratory gyroscope as a turning angular rate sensor employed in a vehicle control system of an automobile body based on a vehicle turning rate feedback system. Such a system detects the direction of a steering wheel itself by a turning angle of the steering wheel. Simultaneously, the turning rate of the car vehicle is detected by the vibratory gyroscope. The system finds a difference by comparing the direction of the steering wheel with the actual body turning velocity, and attains a stable vehicle control by correcting a wheel torque and a steering angle on the basis of this difference. The applicant filed Japanese patent publication 11-281372 A mainly disclosing a vibratory gyroscope suitable for horizontal mounting using a planar vibrator.
When a vibratory gyroscope is produced, a self-oscillating circuit is used to excite driving vibration in a driving vibration arm made of, for example quartz. Further, output voltage from a detection electrode on a vibrator is processed to obtain a value of voltage corresponding to a turning angular rate. Such circuit is disclosed in Japanese patent publication 11-44540A and 2003-87057A.